diff --git a/collects/racket/private/class-internal.rkt b/collects/racket/private/class-internal.rkt
index 239d11374c..d466b4ce0a 100644
--- a/collects/racket/private/class-internal.rkt
+++ b/collects/racket/private/class-internal.rkt
@@ -2576,7 +2576,7 @@
         (fail "no public method ~a" m)))
     (for ([m (class/c-absents ctc)])
       (when (hash-ref method-ht m #f)
-        (fail "class already contains public method ~a")))
+        (fail "class already contains public method ~a" m)))
     (for ([m (class/c-inherits ctc)])
       (unless (hash-ref method-ht m #f)
         (fail "no public method ~a" m)))